It has been proposed that the chemical process installations of a nuclear reprocessing facility may be arranged in a shielded large-area cell. The maintenance work on the process components and conduits must be carried out in a remotely-controlled mode because of the radioactive condition of the cell and because of the need for a short shutdown time of the equipment in the cell. Portable remotely-manipulated machines are provided for that purpose.
A tool for the above-mentioned remote manipulation is an impact wrench with which conduit connections can be disconnected or connected. For this work, it is desirabe that the impact wrench be used in a horizontal operating position and in a vertical operating position as required. In order to achieve this, the impact wrench is mounted in a carrier frame which has either two suspension eyes disposed at different locations or a tilting mechanism for bringing the impact wrench into the two operating positions. The carrier frame is suspended on the crane hook of a cable hoist of a remotely-controlled movable crane. The impact wrench is moved to the work position by means of the crane.
It was found that the impact wrench rotates about the cable hoist when the impact wrench operates in the vertical position. The reaction torque results in a rotary movement of the impact wrench. The rotary movement of the impact wrench twists the crane cable on which the impact wrench is suspended. This causes the cable hoist to lift so that the socket of the impact wrench lifts away from the nut and comes out of engagement therewith.